Semiconductor device applications have experienced significant scaling (reduction in size) over recent years, with continued scaling desirable for a multitude of applications. In addition, semiconductors and semiconductor devices are increasingly used in cross-disciplinary applications, in various configurations, and in unique operating environments.
Many semiconductor applications involve and/or would benefit from the use and implementation of organic semiconductor materials. Organic single-crystal field-effect transistors are useful for the study of charge transport in organic semiconductor materials. In addition, their high performance and outstanding electrical characteristics make them desirable for implementation with electronic applications such as active matrix displays or sensor arrays. For example, organic field-effect transistors are often implemented with organic thin-film transistors (OTFT, or OTFTs). OTFTs are useful for performing a variety of functions and offer unique characteristics desirable for many applications. See, e.g., Sze, S. M. Semiconductor Devices: Physics and Technology, 2nd edition; Wiley: New York, 1981. Generally, many OTFTs are low in weight, flexible in application and/or inexpensively manufactured; as such, OTFTs have been used in a multitude of applications. Other organic semiconductor structures include organic light-emitting diodes, organic lasers, organic solar cells and organic biosensors.
While organic single crystal semiconductors can provide superior performance and outstanding electrical characteristics, particularly in low-cost microelectronics applications (such as active matrix displays or sensor arrays), difficulties in device fabrication have limited their use. Patterning of organic semiconductors is of particular importance, for example to eliminate parasitic current paths (i.e., crosstalk) between neighboring devices. For low cost deposition over a large area, solution-based single crystal deposition and patterning techniques are highly desirable.
Previous approaches to the manufacture of organic materials have been generally limited to the formation of layers or films of organic materials. Approaches to sizing or arranging organic materials have been generally tedious, time-consuming and expensive. In addition, such layers or films are not readily implemented for use with certain applications benefiting from certain shape, orientation or arrangement of organic single crystal materials. In particular, organic single crystal materials are not readily implemented for manufacture on a relatively large scale.
As devices are scaled smaller, cross-talk issues can become more challenging. One approach to reducing or minimizing cross-talk between neighboring devices involves separation of semiconductor materials, such as by patterning an active semiconductor layer. However, with single-crystal organic semiconductor materials, there is often a need to hand-select individual crystals, which presents challenges to producing single crystal devices at high density and with reasonable throughput. In particular, while arrays of inorganic crystals have been patterned over large areas, patterning discrete organic molecular crystals has been particularly challenging.
These and other issues have been challenging to the design, manufacture and implementation of semiconductor devices, and in particular, for those semiconductor devices employing organic semiconductor materials.